1. Field of the Invention
The present invention relates to a technique that enables inter-layer path provisioning to be readily performed in a multilayer transport network.
2. Description of the Related Art
Due to the recent increase in Internet traffic, to simplify a current network structure in which a packet network, a circuit network, and an optical transport network are mixed, and to ensure a transmission quality of future premium Internet Protocol (IP) multimedia traffic, packet-optical integrated network construction and network control technology development may be required. Particularly, as a synchronous optical networking (SONET)/synchronous digital hierarchy (SDH)-centered optical transport network evolves into a dynamic packet transport network, path and resource control technologies based on transport characteristics of packet traffic and service quality may be used.
That is, in a multilayer network in which a single network is configured to have multiple layers, traffic engineering between layers may be used so as to improve efficiency of network by optimizing resources of the network based on all layers rather than separately optimizing the resources for each layer.
Accordingly, the international organization for standardization (ISO) such as Internet Engineering Task Force (IETF), and the like recognizes that a traffic engineering technology through Multiprotocol Label Switching (MPLS) and Generalized MPLS (GMPLS) based on a path computation unit (PCE) is required for inter-layer path setting using optimized resources. Thus, in IETF, function formulation and role of the PCE for provisioning between layers different from a single layer and a Virtual Network Topology Manager (VNTM) for control are required.
For example, three models are provided for inter-layer path computation as follows. First, a model that computes a path in which all layers are integrated through a single PCE is provided. Second, a model that computes an entire path based on path information of layers through a communication between the PCE and a separate PCE for each layer is provided. Third, a model that computes a path only within each layer without an interlocking between PCEs even though the PCE between layers is present is provided.
In addition, similar to the path computation method, several possible models are provided as a path control technology between layers as follows. First, PCE-VNTM cooperation model is provided. In this model, the path setting between layers is performed through role sharing between the PCE and the VNTM. Second, an upper layer signaling model that controls a path through signaling for each layer when a Label Switched Path (LSP) of a lower layer is used based on primarily working signaling entity without the VNTM is provided. Third, a Network Management System (NMS)-VNTM integrated cooperation model that manages a virtual network topology in a view of network management is provided. Finally, an NMS-VNTM separated cooperation model that configures a Traffic Engineering (TE) link through the VNTM only when a lower layer LSP is used in a process of proceeding a path in an upper layer of an NMS in a state in which the PCE is maintained for each existing separated layer is provided. In this instance, there is a need to review advantages and disadvantages for various configurations based on a combination between the NMS-VNTM separated cooperation model and the path computation method.
When path setting between multi-layers is performed by conventional path computation technologies and path control technologies, problems in topology management between the upper layer and the lower layer are generated. In a network node, a specific method for managing topology information between layers, that is, the upper layer and the lower layer in various situations such as in an upper layer node, a lower layer node, and an upper and lower layer integrated node is required. However, all virtual TE links are reflected on the upper layer, and thereby complexity is increased, and a path computation performance of the upper layer is deteriorated.